Bis(haloalkyl)pyrophosphonic acid amine salts

ABSTRACT

NOVEL PYROPHOSPHONIC AND PYROPHOSPHINIC ACID DERIVATIVES AND THEIR AMINE SALTS ARE USEFUL AS LUBRICATING OIL ADDITIVES.

United States Patent Office 3,816,519 Patented June 11., 1974 U.S. Cl.260-502.21 2 Claims ABSTRACT OF THE DISCLOSURE Novel pyrophosphonic andpyrophosphinic acid derivatives and their amine salts are useful aslubricating oil additives.

This is a division of application Ser. No. 776,776, filed Nov. 18, 1968,now U.S. Pat. 3,609,077. This invention relates to novel pyrophosphonicand pyrophosphinic acid derivatives and their amine salts and tolubricant compositions containing such compounds.

It is known in the art that while a number of compounds possessextreme-pressure (EP) properties, only a select few are suitable asadditives to lubricants used in gasturbine engines because of the severeoperating conditions to which these lubricants are subjected. In thisextreme environment many otherwise acceptable extreme-pressure additiveshave been found to be highly corrosive to metals, have contributed tothe deterioration of oils, formation of deposits, loss of oxidationstability, and, in general, have caused the lubricant to fail one ormore of the stringent specifications placed on lubricants of this type.

One of the most suitable extreme-pressure additives presently used ingas-turbine engine lubricants is the amine salt ofmonochloromethylphosphonic acid which is described in U.S. Pats.2,777,819, 2,858,332, 2,874,120 and 2,882,228. Several other suitableextreme-pressure additives are also available, but none of these isentirely satisfactory in meeting the ever increasing requirements forthese products. The development of new extreme-pressure additives whichcontribute to the load carrying capacity and stability of the lubricantcomposition while not adversely affecting its other properties would beextremely desirable.

It has now been found that certain novel pyrophosphonic andpyrophosphinic acid derivatives are beneficial in imparting extremepressure and other properties to lubricating compositions and areespecially suitable as additives to lubricants used in gas-turbineengines. It has been further found that the amine salts of these acidsare particularly advantageous for imparting said properties to lubricantcompositions.

The pyrophosphonic and pyrophosphinic acid derivatives according to thepresent invention are represented by the formula:

wherein R and R are alike or dissimilar monoto perhalo alkyl groupshaving from 1 to 4 carbon atoms; and B and B are hydroxyl groups, R or Ras defined above. B and B can be alike or dissimilar. The haloalkylgroup may contain fluorine, chlorine or bromine atoms or combinationsthereof. Typical haloalkyl groups include but are not restricted to thefollowing: monochloromethyl, l-monochloroethyl, 2-monochloroethyl,l-monochloropropyl, 1,3-dichloropropyl, dichloromethyl, l-chloro-Z-methylpropyl, l-chlorobutyl, 1,3-dichlorobutyl, l-chloro- 1methylpropyl, perchloromethyl, 1,1 dibromoethyl, monobromomethyl,dibromomethyl, monofiuoromethyl, 1,1-difiuoroethyl, 1,3-difluoropropyl,difluoromethyl and the like. Haloalkyl groups having from 1 to 2 carbonatoms with at least one halogen atom substituted on the alpha carbon arepreferred. Compounds wherein R and R are monoor dichloromethyl groupsare particularly suitable for the purposes of this invention.

Any of the above described pyrophosphonic and pyrophosphinic acidderivatives having at least one hydroxyl (OH) group can be neutralizedwith a primary or secondary amine to form an acid/amine salt. This classof compounds, i.e., haloalkylpyrophosphonic acid/amines andhaloalkylpyrophosphinic acid/ amines have been found to be especiallysuitable extreme-pressure additives in lubricant compositions. Aparticularly advantageous salt is the primary amine salt ofbis(monochloromethyl)pyrophosphonic acid.

The acid derivatives of this invention can be prepared by reactinghaloalkyl phosphonic or phosphinic acids with dicyclohexylcarbodiimide.The resultant product has a pyrophosphate structure and is essentiallythe anhydride of the reactant acid. A detailed description of the methodof preparing these compounds is given in the examples. The acid/ aminesalts are formed by stoichiometric neutralization of the acid with aprimary or secondary amine.

Amines which form effective salts according to this invention areprimary and secondary alkyl amines having from 8 to 30 carbon atoms permolecule. Branched tertiary-alkyl primary amines are preferred; branchedin this context means having at least two hydrocarbon substituentsattached to the main carbon chain. As the tertiary-alkyl, the radical ofpolyisobutylene and polypropylene, and mixtures of these areparticularly preferred. Examples of these amines are1,1,3,3-tetram'ethylbutylamine, 1,1,3,3,5,5-hexamethylhexylamine,1,1,3,3,5,5,7,7- octamethyloctylamine and1,1,3,3,5,5,7,7,9,9-decamethyldecylamine. Tertiary alkyl methyl primaryamines, such as 2,2,4,4-tetramethylpentylamine and2,2,4,4,6,6-hexamethyl hexylamine, are also suitable.

Other primary amines which are effective in forming the salts of thisinvention are described in Bortnick, U.S. 2,606,923, issued Aug. 12,1952 and Bortnick, U.S. 2,611,- 782, issued Sept. 23, 1952. Theseinclude tert-tridecylamine,

OzHs

( hHs as well as isoheptyl diethyl carbinylamine, isooctylethylpropylcarbinylamine, etc. Primary amines of this type are commerciallyavailable from Rohm and Haas Company under the trade name of Primenes.'Ihe amine may also be a polyamine, such as a diamine or triamine, andmay contain other non-reactive groups, such as amide or ether groups, inthe carbon chain.

Some specific examples of secondary amines suitable for making thepyrophosphonic and pyrophosphinic acid salts are diamylamine,dihexylamine, di(2-ethylhexyl)amine, dioctylamine, didecylamine,didodecylamine, ditetradecylamine, dihexadecylamine, dioctadecylamine,dibromodioctadecylamine, isopropyloleylamine, diricinoleylamine,butylricinoleylamine, butyl-2-ethylhexylamine, dilaurylamine,methyloleylamine, ethyloctylamine, isoamylhexylamine, dicyclohexylamine,dicyclopentylamine, cyclohexyloctylamine, cyclohexylbenzylamine,benzyloctylamine, benzyl-2-ethylhexylamine, allyloctylamine,dodecyl-2-ethylhexylamine, (l-isobutyl 3methylbutyl)-3,3,3-methylcyclohexylamine, di(l isobutyl 3 methylbutyl)amine;

N-n-dodecyldiethylenetriamine, N-n-tetradecyldiethylenetriamine,octylethylene diamine, N-Z-ethylhexyl N-hexadecyl triethylene tetramine,heptyl trimethylene diamine, N-tetradecyl tripropylene tetramine,N,N'-dially1 trimethylene diamine, 3-hexyl-morpholine, and the like.

The following examples are illustrative of the compounds of thisinvention and the manner of their preparation.

EXAMPLE I Bis(monochloromethyl)pyrophosphonic acid I] llClOHa-P-O-P-CHzCl A 3-neck, 500 ml. flask equipped with a condenser,thermometer, dropping funnel, and magnetic stirring bar was charged with200 ml. of anhydrous diethyl ether and monochloromethylphosphonic acid(26 g.; 0.2 mole). A solution of 100 ml. of diethyl ether anddicyclohexylcarbodimide (DCCD, 20.6 g.; 0.1 mole) was added slowly atroom temperature. The mixture was stirred overnight at room temperature.The mixture was filtered and the solvent removed in vacuo. A yellowviscous oil was obtained which slowly crystallized upon standing. Ayield of 90% was obtained.

EXAMPLE II Bis(dichloromethyl)pyrophosphonic acid ll llCl2GH-P-O-P-CHC1:

The same conditions, apparatus, and procedure used in Example I wasemployed in this reaction. Dichloromethylphosphonic acid (0.1 mole) andDCCD (0.05 mole) were the starting materials. A yield of 85% wasobtained.

EXAMPLE III Tetrakis(monochloromethyl)pyrophosphinate The sameconditions, apparatus and procedure used in Example I involvingdicyclohexylcarbodimide (DCCD) were repeated in this reaction.Bis(chloromethyl)phosphinic acid (40.8 g.; 0.25 mole) and DCCD (15.8 g.;0.125 mole) were the reactants. A white solid was obtained in 89% yield.

EXAMPLE IV Tris (monochloromethyl) pyrophosphinic acid Into a 3-neck,100 ml. flask equipped with condenser, addition funnel, and mechanicalstirrer were added DCCD (20.63 g.; 0.10 mole) and 350 ml. of anhydrousdioxane (distilled from lithium aluminum hydride).Monochloromethylphosphonic acid (13.0 g.; 0.10 mole) was dissolved in100 ml. of dioxane and added dropwise at 0 C. over a four-hour period.After stirring for an additional hour, bis(chloromethyl)phosphinic acid(16.2 g.; 0.10 mole) in 100 ml. of dioxane was added dropwise at roomtemperature. The mixture was filtered and the solvent removed bydistillation. The urea was recovered in 95% of theory. The product wasobtained in 85% yield.

The acid-amine salts of the following examples were prepared by theneutralization of the acids of Examples I, II and IV with a primaryamine. The types of amines suitable for this invention have beenpreviously described in detail. In these examples a, primary C -C aminewith a tertiary alkyl structure was used. This material is commerciallyavailable from Rohm and Haas under the trade name of Primene J MT. Forthe sake of brevity the letters J MT are used in the following examplesto represent this amine.

EXAMPLE V Bis(monochloromethyl)pyrophosphonic acid/Primene J MT aminesalt EXAMPLE VI Bis dichloromethyl pyrophosphonic acid/Primene J MTamine salt EXAMPLE VII Tris(monochloromethyl)pyrophosphinic acid/PrimeneJ MT amine salt The pyrophosphonic and pyrophosphinic acid derivativesand the acid-amine salts of this invention can be added to mineral oilas Well as synthetic lubricating oils, but are particularly useful insynthetic oils which are used under more extreme conditions where theadvantages of these compounds are more pronounced. Synthetic lubricantssuitable for the invention are of various types, such as aliphaticesters, silicones, polyalkylene oxides, polyphenyl ethers, fluorinatedhydrocarbons, polyolefins, and phosphate esters. Examples of siliconesinclude methyl silicone, methylphenyl silicone, methylchlorophenylsilicone, etc. Examples of polyalkylene oxides are polyisopropyleneoxide, polyisopropylene oxide diether, and polyisopropylene oxidediester. Fluorinated hydrocarbons include fluorinated oils andperfiuorinated hydrocarbons.

Preferred synthetic lubricant base stocks are esters of alcohols having1 to 20, especially 4 to 12, carbon atoms and aliphatic carboxylic acidshaving from 3 to 20, especially 4 to 12, carbon atoms. The ester basemay be a simple ester (reaction product of a monohydroxy alcohol and amonocarboxylic acid), a polyester (reaction product of an alcohol and anacid, one of which has more than one functional group), or a complexester (reaction product of a polyfunctional acid with more than onealcohol, or of a polyfunctional alcohol with more than one acid). Also,excellent synthetic lubricants may be formulated from mixtures ofesters, such as major proportions of complex esters and minor amounts ofdiesters.

Examples of suitable ester base oils are ethyl palmitate, ethyl laurate,butyl stearate, di-(2-ethy1hexyl) sebacate, di-(2-ethylhexyl) azelate,ethyl glycol dilaurate, di- (Z-ethylhexyl) phthalate,di-(1,3-methy1buty1) adipate, di-(l-ethylpropyl) azelate,diisopropyloxylate, dicyclohexyl sebacate, glycerol tri-n-heptoate,di(undecyl) azelate, and tetraethylene glycol di-(Z-ethylene caproate),and mixtures thereof. An especially preferred mixture of esters consistsof about 50 to wt. bis(2,2,4-trimethylpentyl) azelate and 20 to 50% wt.1,1,1-trimethylyl propane triheptanoate.

Especially preferred esters for use as base stocks in the presentinvention are esters of monocarboxylic acids having 3 to 12 carbons andpolyalcohols, such as pentaerythritol, dipentaerythritol, andtrimethylolpropane. Examples of these esters are pentaerythritylbutyrate, pentaerythrityl tetrabutyrate, pentaerythrityl tetravalerate,pentaerythrityl tetracaproate, pentaerythrityl dibutyratedicap roate,pentaerythrityl butyratecaproate divalerate, pentaerythrityl butyratetrivalerate, pentaerythrityl butyrate tricaproate, pentaerythrityltributyratecaproate, mixed C saturated fatty acid esters ofpentaerythritol, dipentaerythrityl hexavalerate, dipentaerythritylhexacaproate, dipentaerythrityl hexaheptoate, dipentaerythritylhexacaprylate, dipentaerythrityl tributyratecaproate, dipentaerythrityltrivalerate trinonylate, dipentaerythrityl mixed hexaesters of C fattyacids and trimethylolpropane heptylate. Pentaerythrityl esters ofmixtures of C acids are excellent base oils, and are commerciallyavailable from Hercules Chemical Company. Preparation of suitable estersis described in Eichemeyer, US. 3,038,859, issued June 12, 1962, andYoung, US. 3,121,- 109, issued Feb. 11, 1964.

In addition to the aforementioned synthetic oils the additives of thisinvention may also be incorporated in mineral lubricating oils. Themineral lubricating oil can be obtained from paraflinic, naphthenic,asphaltic or mixed base crudes and/ or mixtures thereof, for exampleneutral oil, oils having viscosities of from 100 to 6500 SSU at 100 F.

The pyrophosphonic or pyrophosphinic acids and their amine salts may beadded either separately or in combina tion to the synthetic or minerallubricating oils in the amount of from 0.01% to about 5% by weight.

Other additives can also be incorporated into the lubricatingcompositions according to the present invention. For example, any of theadditives recognized in the art to perform a particular function orfunctions, i.e. viscosity index improvers such as methacrylic polymers;antioxidants, such as amines, phosphorus or phenolic compounds, i.e.phenyl-alpha-naphthylamine, dioctyldiphenyl amine; zinc dialkyldithiophosphate, or 4,4-methylene bis(2,6-dit-butylphenol); anti-foamagents; corrosion inhibitors; anti-rust agents and the like can be used.

The remarkable effectiveness of the compounds of this invention inimparting improved load-carrying ability to lubricant compositions isdemonstrated by the results shown in Table I. Blends of syntheticlubricant base stock, i.e. mixed C -C pentaerythrityl ester, and thecompounds of Examples IH, VI and VII were prepared and theirloadcarrying capacities determined by the Ryder Gear Test conductedunder the conditions outlined in military specification MIL-L-23 699.The Ryder Gear Tester was developed by Pratt and Whitney in 1941 toevaluate lubricants of high speeds by observing the scuff on a pair ofaircraftquality gears to which a load is applied while the machine is inmotion. Results are reported in terms of pounds per inch of tooth width.A complete description of this test is given in ASTM Bulletin No. 184,p. 41, September 1952. The concentration of the additives was adjustedso that each of the blends had an equivalent phosphorus content. Theload-carrying capacity of the synthetic base stock without any additivewas determined for comparative purposes.

As previously mentioned, extreme-pressure additives suitable for use insynthetic gas-turbine lubricants must TABLE II Wt. percent Composl-Composi- Additives tion A tion Monoehloromethylphosphonic acid/J MT '0.20 BiIsfiuIonochloromethyl)pyrophosphonic acid/ '0. 12Phenyl-alpha-naphthylamine 1. 0 1. 0 Acryloid HF-844 (methacryliepolymer)- 0. 25 0.25 Benzo 0. 05 0. 05 Bis-benzotriazole 0. 05 0. 05p,p-Dioctyldiphenylamine 2. 0 2. 0 Base stock (mixed (ls-Capentaerythrityl ester). Balance Balance *Concentrations of the EPadditives which provide compositions of equal phosphorus content.

Compositions A and B as described above were tested to determine theirload-carrying capacity, their tendency to form deposits, and theircorrosiveness to lead. The results of these tests are shown in TableIII.

TABLE III SOD lead Eppl vaporcorrosion, mg. Ryder gear phase eoker test,average test, deposit At 325 At 375 rating, lb./in. weight net, g. F., 1hr. F., 5 hr.

Composttion:

Eppz' Vapor-Phase Coker Test-This test is used to predict the amount ofvapor phase coking, i.e. carbon deposits found in bearing cavities orbreather tubes of gas-turbine engines, that would occur in an enginetest.

SOD Lead Corrosion Test-This test indicates corrosivity towards lead andis described in Fed. Test Method Std. No. 791a Method 5321.1. Specifiedlimits at both 325 F. and 375 F. are :60 mg.

In order to determine their corrosion and oxidation stability,Compositions A and B were tested in accordance with Pratt and WhitneyAircraft 521B specification at 425 F. for 48 hours. The results of thesetests and the specification limits are shown in Table IV.

Composi- Specified Composilimits tion B tion A Magnesium, mg./crn. =23.0 0. 13 0. 00 Aluminum, rug/cm. i3. 0 +0. 01 0. 01 Copper, mg./em.z i3.0 0. 26 0. 26 Iron, mg./em. i3. 0 +0. 03 0. 01 Silver, mgJcmJ- i3. 0 +0.04 0. 00 Titanium, mg.lcm. +0. 01 01 Change in acid numb 1. 40 0.8Change in viscosity F.), per

cent 1 50.0 26. 4 25. 8

1 Max.

The two compositions were also subjected to the Alcor Deposition Testwhich gives a further measure of the stability of the lubricants inrespect to deposit formation. A detailed description of this test isgiven in Proceedings of the USAF-Southeast Research Institute TurbineLubrication Conference, Sept. 13-15, 1966, Southwest Research Institute,San Antonio, Texas, pg. 152. The results of this test are summarized inTable V.

TABLE V.-ALCOR DEPOSITION TEST Composi- Composition A tion B Criticaltemperature, F 600 505 Tube deposition rating RC scale 24. 4 27. 8 Tubedeposits, mg 11. 0 l0. 4 Filter deposits, mg. 30. 0 7. 6 Overall rating37. 2 22. 9 Oil consumption, In 150 110 Viscosity, 100 F, cs. after 0 hr29. 9 27. 6 34. 0 31. 48 hr 36. 9 34. 4 Viscosity change, 100 F., 481113, percent +23. 3 +25.9 Acid number after- 0. .25 0.13 0. 36 0. 17 48hr 0. 42 0. 26 Acid number change, 48 0.17 +0. 13

The data presented in Table IH indicate that Composition B containingone of the novel pyrophosphonic acid derivatives of this invention notonly has greatly improved load-carrying ability but also has goodstability and is less corrosive to lead. The results shown in Table IVindicate that Composition B is slightly less corrosive to the metalstested than is Composition A and also exhibits less of an acid numberchange. As shown in Table V, Composition 13 produces a lower overalldeposit rating than Composition A indicating the pyrophosphonic acid/amine salt provides greater stability than the monochloromethylphosphonic acid/ amine of the prior art.

The novel compounds of the present invention therefore represent a classof additives which not only impart good load-carrying capacity tolubricant compositions, but also provide stable compositions with goodantioxidation and anti-corrosion properties.

We claim as our invention:

1. An amine salt of the compound of the formula References Cited UNITEDSTATES PATENTS 3,600,435 8/1971 Randall et a1 260-5024 P 2,858,33210/1958 Watson et al. 260--l.2l 2,063,629 12/1936 Salzber-g et al.260-545 P 2,877,629 4/1957 COOVer et a1 260545 P 2,882,308 4/1959Kwistek 260-5024 P 2,841,611 7/1958 Bersworth 260545 P OTHER REFERENCESMoedritzer: I. Am. Chem. Soc., Vol. 83 (1961), pp. 4381-4, QOIAS.

JOSEPH E. EVANS, Primary Examiner US. Cl. X.R.

